Collet



June 13, 1939. c, SUTTON COLLET Filed Aug. 22, 1938 INVENTOR Klara M Szzfzorg.

ATTORNEYCE Patented June 13, 1939 UNITED STATES PATENT OFFICE COLLET Clarence M. Sutton, Detroit, Mich.

Application August 22, 1938, Serial No. 226,030

7 Claims.

from the machine upon which it is mounted or the removal of other parts of the machine to effect replacement of the pads or jaws.

Objects of the invention include the provision of a collet comprising a main body portion having a bore and a plurality of pads receivable in the bore, the pads and main .body portion being provided with cooperating surfaces limiting radial movement of the pads with respect to the main body portion; the provision of a construction as above described in which the main body portion and the pads are provided withradially overlapping surfaces cooperating to maintain the pads in their proper radial position with respect to the main body portion; the provision of a construction as above described in which the pads are insertable into the bore of the main body portion from one end of the main body portion; the provision of a construction as above described in which means insertable in an axial face of the main body portion is provided for limiting relative rotational movement between the pads and the main body portion; and the provision of a collet having removable pads or jaws within the bore thereof so constructed and arranged as to permit application and removal of the pads through an end of the collet, the main body portion and the pads being so constructed and arranged as to maintain the radial relationship between the, pads and the collet, together with means operable through an axial face of the main body portion for limiting relative rotational movement of the pads with respect to the main body portion.

The above being among the objects of the present invention, the same consists in certain novel features of construction and combinations of parts to be hereinafter described with reference to the accompanying drawing, and then claimed, having the above and other objects in view.

In the accompanying drawing which illustrates a suitable embodiment of the present invention and in which like numerals refer to like parts throughout the several diflerent views,

(Cl. 29-s2) Fig. 1 is a partially broken, partially sectioned side elevational view of a collet constructed in accordance with the present invention, the section being taken in a plane passing diametrically therethrough;

Fig. 2 is a front end view of the collet shown in Fig. 1;

Fig. 3 is a slightly enlarged fragmentary sectional view takenon the line 3-3 of Fig. 2;

Fig. 4 is a fragmentary transverse sectional view taken on the line 4-4 of Fig. 3;

Fig. 5 is a perspective view of one of the pads shown mounted in the previous views. 1

As is commonly understood by those skilled in the art collets are commonly employed in connection with machine tools of the lathe type, and particularly hand and automatic screw machines, for the purpose of chucking bars or the like while being machined. Such collets include a hollow and generally circular main body portion provided at one end with a tapered or frusto-conical surface or surfaces. Such main body portion is provided with a plurality of slots through the walls thereof which slots extend from the tapered end of the main body portion to a point adJacent but spaced from the-opposite end of the main body portion whereby the tapered end of the main-body portion is radially yieldable. A surrounding support, or part associated there.- with, adapted to be rotated by a machine tool upon which the collet is mounted is provided with surfaces complementary to the coned surface of the collet and means are provided for effecting I relative axial movement between the tapered surface of the collet and the support to effect a radial contraction'of the tapered end of the collet thereby to cause the collet to grip a piece of work received therein. Conventional collets are usually provided with three or four of the axially directed slots above mentioned. Three such slots 40 are usually provided in. collets adapted to chuck round work and work of almost any cross-sectional configuration vexcept square work where four equally angularly spaced slots are considered necessary. The bore of such collets may be shaped to conform to the cross-sectional configuration of the work to be held therein although it will be apparent that where any work is of a cross-sectional configuration uniformly disposed about its central axis it may be received and held within a collet having a cylindrical bore.

One type of collet that is conventionally employed in connection with screw machines, both hand and automatic, is what is known as amaster collet having interchangeable pads or jaws. 5:5

In this type of collet the bore of the collet at v the front end thereof is provided with a so-called pad for each angularly disposed section or segment thereof, .the pads being conventionally removable so that by removing one set of pads and replacing them by another set of pads of different thickness, the effecting bore of the collet, and therefore the diameter of the work receivable by the collet, may be varied. By this means a single master collet with two or more sets of removableor replaceable pads may be employed for chucking as' many diiferent sizes or cross-sectional conflgurations of work as there are sets of pads to correspond. Furthermore, inasmuch as the Bripping surfaces of a collet constitute the points where the greatest wear occurs, when a set of pads wears to such an extent as to require replacement, replacement of the pads only is necessary to re-condition the collet and this effects a considerable saving in tool costs.

The present invention relates to the master collet and interchangeable pad type of construction.

In the past it has been the practice to secure such pads in the interior of the collet by means of more or less radially directed screws extending through each angularly disposed section or segment-oi the main body portion of the collet and threading into th'eindividual pads. Such method of securement not only looks the pads to the collet against relative radial movement butalso locks the pads against relative rotational movement with respect to the main body portion. However, the above conventional method of 'securing pads to master collets requires removal of the collet from the machine, particularly with automatic screw machines, in order to remove and replace the pads, and in hand screw machines requires the removal of a plate over the nose piece of the machine in order to permit access to the'screws which removably secure the pads to the main body portion of the collet. The

I removal of collet in the one case and of such plate in the other case requires the expenditure of a material amount of time during which the machine is, of course, down or out of operation and particularly in some instances the time. required to change the pads in a collet constitutes a material loss to the owner of the machine.

The present invention provides a construction whereby such padsmay be removed and replaced in a collet of the type described without the necessity of removing the collet from the machine or the necessity of removingany plate which may be mounted upon the nose'of the machine. The invention is applicable Qtocollets' generally, regardless of the direction of relative-axia1 movement between the collet; anditslsupport required to effect contraction of the collet, the number of axially directed slots in the mainbody portion of the collet, and regardless of the type of the machine to which the collet is. adapted. For the purpose of illustration only the collet'shown' in the drawing is assumed ,to be of; that typein which-the active coneface of they collet con- :vergestoward the'front face thereof and'that the collet is provided with three qually angularly 'space'd's'lotsin the main body portion'thereof, it

be ng-understood that in the broad invention: the activel tapered suriace'of the collet may face in 'li'i either-direction and" that any suitable or de- 1 sirable number of. slots may, be employedg,

g-nowto Figs. 1 to .5, inciusi'vaijbe portion of the coilet is indicated 8.-

it comprises a generally cylindrical central portion l2 of slightly increased diameter at-its rear end as at I4 to provide a radial bearing face. The opposite or forward end of the main body portion .III is formed to provide a pair of oppositely facing frusto-conical surfaces, namely the rearwardly facing frusto-conical surface I6 and the forwardly facing frusto-conical surface IS, the latter being considered as the operative cone face in the present instance. Also as in conventional constructions the main body portion III is provided with three equally angularly spaced slots 20 each slot 20 lying in a plane extending radially with respect to the axis of the main body portion l0 and extending from the front face of the collet to a point adjacent but spaced from the rear end thereof,

this permitting a limited amount of radial movement of the three segments thus formed at the front end of the collet and yet maintaining the main body portion as an integral part.

The main body portion I0 is provided with a generally cylindrical bore within the forward end ofwhich is received three pads 22, one corresponding to each of the segments formed by the slots 20. It is the particular cooperation between the pads 22 and the main body portion ID that constitutes the present invention. Broadly speaking the present invention is directed to a construction by means'of which the pads 22 may be inserted into the bore of the main body portion through the front end thereof and yet be secured against relative radial displacement from their intended position against the bore of the main body portion without the necessity of access to any face of the main body portion except the front axial face thereof. While this may be accomplished in a number of different ways once the principle of the present invention is known, the construction shown in Figs. 1 and 5 by way of illustrating the broad principles of the invention has proven itself to be commercially practicable.

In the particular construction shown in Figs. 1 to 5, all of thepads of any particular set of pads may be identical as far as size, shape and contour are concerned. In other words, each of the pads 22 extends over the same are of a circle and all of the pads are of the same length, thickness,

internal and external diameter. In the particular construction of the pads 22 shown their radially inner faces cooperate to form a cylindrical opening for reception of the stock or piece of work to be acted upon, and such radially inner faces are preferably knurled or otherwise roughened as indicated to provide a more secure grip upon the work received thereby. The opposite axial or end faces of the pads 22 adJacent the periphery thereof are axially grooved or undercut as at 24. The bore of the main body portion in adjacent the front end of the main body portion is radially relieved so as to form. an annular -to the effective diameter of the radially outer face of the pads 22 and the axial or end walls of which are formed to provide axially directed opposed tongues 28 complementary in shape to the grooves 24 in pads 22 and so spaced as tobe relatively closely received in the grooves 24 when arranged in complementary relationship thereto. In the particular construction shown the grooves 24 and consequently the tongues 28 are of V-like formation so that the interengagement between each of the pads 22 and the main body portion I0 is of a more or less dovetail-like nature thus to hold the pads 22 against relative radial movement with respect to their complementary segmental portion of the main body l0, it being understood, however, that the particular conformation of the thus radially interlocking parts of the pad and main body portion may be of any desired shape or conformation to maintain this radial interlocking feature.

The formation of the recess 26 in the bore of the main body portion l0 provides a radially inwardly directed circularly extending lip 30 at the front end of the main body II). In order to permit insertion and removal of the pads 22 this lip 30 is cut away as at 32, best shown in Fig. 2, over an are slightly greater than the arc of the pads 22 and located equally on either side of the slot 20 between two of the adjacent segments at the front end of the main body l0. By this means all three pads 22 may be inserted into the recess 26 by inserting them one at a time in an axial direction through the front end of the main body l0 and then rotating such inserted pad in the recess 26 to bring it out of alignment with the cut out portion 32, until all pads of the set have been inserted. Then all of the pads of the set are rotated simultaneously to bring them into angular alignment with their respective segments of the main body portion in which position all of the pads will be both radially and axially interlocked with the main body portion through the inter-engagement of the grooves 24 and tongues 28. Likewise removal of a set of pads from the main body portion may be accomplished by rotating all of the pads 22 therein until one is aligned with the cut out portion 32 and then removed therethrough, rotating the remaining pads successively into alignment with the cut out portion and removing them through the cut out portion 32.

It is, of course, desirable, if not necessary, in order to prevent relative rotational movement between the pads 22 and the main body portion It), not only to prevent the possibility of any wear occurring between the cooperating surfaces of the pads and main body portion but also to prevent the possibility of a pad becoming aligned with the cut out portion 32 and being displaced therethrough, to lock the pads 22 against such relative rotational movement. While this may be accomplished in a number of suitably different ways, one effective way is illustrated as comprising an axially parallel hole.34 drilled into 'the front face of the main body portion III with its axis aligned with'the bottom of the recess 26, thus providing a completely circular hole in the front face of the main body portion l0 partly within'the lip 30 and intersecting the recess 26 within the main body portion. The peripheral surface of at least one of the pads 22 is provided with a semi-cylindrical recess 36 therein which may be brought into registry with that portion of the hole 34 intersecting the recess 26 whereby to complete a cylindrical opening lying partially within such pad 22 and partially within the main body portion Ill.

The outer end of the hole 34 is threaded and receives therein the outer threaded end of a pin 36 insertable through the front axial face of the main body portion l0 and relatively closely received within the cylindrical openings thus lying partially within the main body portion l0 and partially within one of the pads 22. As will be appreciated this provides a key forming positive lock between such pad and the main body portion HI for locking these parts against relative rotational movement with respect to each other. It

will also be appreciatedthat the hole or holes 34 are so related to the recesses 36 in the pads 22 as to maintain each pad 22 in angular alignment with the corresponding segments of the main body portion III with which it is adapted to cooperate.

While each of the pads 22 may be provided with a recess 36, a corresponding number of holes 34 provided in themain body portion l0, and a pin 38 provided for cooperation between each pad and the main body portion I 0, it has been found sufficient to lock only one of the pads 22 against relative rotation in the manner described, the locking of this one pad 22 effectively locking the remaining pads of the set against all except the most limited amount of relative rotational movement. The use of a single locking pin 38 is desirable inasmuch as it reduces the total number of parts in the structure. Also while all the pads 22 may be provided with the semi-cylindrical recess 36 even where only one pin 38 is employed, so that all pads of a set will be identical, itis only necessary that one of the pads 22 be thus provided, thus reducing the machining operations required in the manufacture of the pads.

- It will be readily understood from the foregoing that by the construction provided in accordance with the present invention, master collets may be provided with replaceable pads or jaws that are insertable into and removable from the master collet from the front axial face thereof, that they are readily locked'against relative axial movement with respect to the master collet without the necessity of access thereto from any face except thefront axial face thereof, and that they are easily and readily secured against relative rotational movement with respect to the master collet from the front'axial face only of the master collet. Accordingly, it will be appreciated that the pads or jaws may be quickly and easily replaced without the necessity of removing either the collet or any nose piece or plate cooperating or associated with the front end of the collet. Those skilled in theart will readily understand that the construction permits replacement of such pads or jaws in a master collet in a fraction of the time required with master collets of conventional construction. It will also be understood that the pads 22 will ordinarily be provided in a plurality of sets each set being of different thickness so as to provide for receiving various diameters of stock to be worked upon, or of various internal configurations to accommodat'e stocks of various cross-sectional configuration. As previously stated it will be appreciated that the construction is susceptible to various modifications in form, arrangement and coaction of parts in accordance with the present invention and, accordingly that formal changes may be made in the specific embodiment of the invention described without departing from the spirit or substance of the broad invention, the scope of which is commensurate with the appended claims.

What I claim is:

1. In a master collet construction, a main body part, a pad part adapted for reception in said main body part, each of said parts having an axially projecting portion adjacent each end of said pad part, and said portions at corresponding ends of said pad part being arranged in' 2. In combination, a master collet including a hollow body having a plurality of angularly arranged radially yieldable segments, a pad for -each of said segments received in the bore of said collet, oppositely directed axially projecting portions in said bore, and oppositely directed axially projecting portions on each of said segments, said projections 'on said segments being arranged in axially interfltting and radially overlapping relation with said projecting portions in said bore whereby to maintain said pads against relative radial movement with respect to their corresponding segments.

3. A master collet having a pads received in said bore and arranged circularly thereof, said collet and said pads having cooperating radially overlapping surfaces at each end thereof normally maintaining said pads against radially inward movement in said bore with respect to said collet, and means operable from an axial face of said collet cooperating between at least one of said pads and said collet for limiting relative rotational movement between said pad and collet.

4. In combination, a 'collet having a bore, an annular recess insaid bore, the end walls of said recess formed to provide axially directed projecting portionsextending toward one another and with the tips of said projection arranged in radially spaced relation with respect to the bottom wall of said recess. a plurality of circularly arranged padseach having an arcuate .outer surface conforming in curvature to the bottom wall of said recess and each having an axially directed projection onthe opposite axial end walls thereof, said projecting portions on said pads axially overlapping said projecting portions on said collet lying radially outwardly thereof whereby to provide radially overlapping portions on said pads and said collet at each end of said pad for holding said pads against relative radial movement with respect to said collet.

5. In combinatioma collet having a bore, an

' annular recess in said bore, the end walls of said recess formed to provide axially directed projecting portions extending toward one another and with the tips of said projection arranged in radially spaced relation with respect to the bottom wall of said recess, a plurality of circularly arranged pads each having an arcuate outer surface conforming in curvature to the bottom wall of said recess and each having an axially directed projection on the opposite axial end walls thereof, said projecting portions on said pads axially overlapping said projecting portions on said collet lying radially outwardly thereof whereby to provide radially overlapping portions on said pads and said collet at each end of said pad for holding said pads against relative radial movement with respect to said collet, and means for probore, a plurality of jecting through an axial face of said collet arranged in intersecting relation with respect to e both the bottom wall of said recess and the radialof at least one of said pads, locking. said pads. against relative rotation withrespect' ly outer wall to said collet. v

6..In combination, a collect having a bore, an

annular recess in said bore, said recess extending Y to a point adjacent the front end of said collet whereby to form in effect a radially inwardly directed lip at the front end of said collet, the end walls of said recess formed to provide axially directed projecting portions extending toward one another and with the tips of said projection arranged in radially spaced relation with respect to the bottom wall of said recess, a plurality of circularly arranged pads each having an arcuate outer surface conforming in curvature to the .bottom wall of said recess and each having an axially directed projection on the opposite axial end walls thereof, said projecting portions on said pads axially overlapping said projecting; portions on said collet lying radially outwardly thereof whereby to provide radially overlapping portions on said pads and said collet at each end of said pad for holding said pads against relative radial movement with respect to said collet, said lip being removed over a portion of its angular extent whereby to permit insertion and removal of said pads to and from said recess in an axial direction therethrough.

7. In combination, a collet having a bore, an annular recess in said bore, said recess extending to a point adjacent the front end of said collet whereby to form in effect a radially inwardly directed lip at the front end of said collet, the end walls of said recess formed to provide axially directed projecting portions extending toward one another and with the tips of said projection arranged in radially spaced relation with respect to the bottom wall of said recess, a plurality of circularly arranged pads each having an arcuate outer surface conforming in curvature to the bottom wall of said recess and each having an axially directed projection on the oppdsite axial end walls thereof, said projecting portions on said pads axially overlapping said projecting portions on said collet lying radially outwardly thereof whereby to provide radially overlapping portions on said pads and said collet ateach end of said pad for holding said pads against relative radial movement with respect to saidcollect. said lip being removed over adjacent portions of adjacent segments to an extent slightly. in excess of the arcuate dimensions of said pads whereby to persaid recess therethrough.

mit insertion and removal of said pad to and'from 

